On the tp-link er605, when i activate ipv6, doh stops working even with dns proxy activated. After disabling IPv6, doh works again.  Testing using Firefox without doh active. 

1. I disable IPv6 and the DOH works in the Cloudflare test. 

2. activate ipv6 the doh stops working in the cloudflare test. 

3. ipv6 activated and activate doh in Firefox the doh test works in the cloudflare test. 

4. ipv6 enabled with doh on Firefox disabled and private dns on Android enabled. option 1. dns one.one.one and test cloudflare switches to dns over tls. option 2. cloudflare-dns.com and test cloudflare passes to doh. 

Apparently DNS proxy does not work with IPv6 activated in standalone mode.  Anyone with IPv6 enabled and DOH enabled in the DNS

proxy?

 any suggestion.